The present invention relates generally to a coin release device, in particular to a simplified and improved coin release device to be used in a payphone.
Payphones are operable by receiving coins deposited therein. Such payphone is usually equipped with a coin release device arranged inside the casing of the phone and in mechanically coupling with a coin release lever which is located outside the phone casing and accessible by phone users.
A prior art coin release device includes a base plate, a driving link, a driven link and a biasing spring. The base plate is fixed inside the payphone casing and has a pivot pin extending therefrom to be rotatably supported by the driven link having two opposite arms. One arm has a pin formed thereon and the other one rotatably supports a coin release roller adapted to be cooperated with a coin receiving device. The driving link has an elongated slot into which the pin of the driven link extends and drivingly engages. The shaft of the driving link extends outside the payphone casing and is connected to a user-actuateable lever so that by actuating the lever, the driving link is rotated to drive, through the connection between the elongated slot and the pin, the driven link may rotate about the pivot. A biasing spring is provided between the driving link and the base plate to bias the driving link toward an un-actuated position defined by contact engagement between an extension of the driving link and a stop provided on the base plate.
Although the current technology is more simplified and practical when compared with conventional arts, it still suffers from several drawbacks described as follows:
1. An elongated slot is designed at one end of the driving link to intentionally drive the pivot pin located on the driven link. Such elongated slot requires complicated manufacture process and thus induces additional cost.
2. The lateral dimension of the elongated slot requires high accuracy to guarantee a linear motion of the corresponding pivot pin along the longitudinal direction of the elongated slot; otherwise, the user-actuateable lever will have to be tilted to be able to start actuating and therefore impair the product quality.
3. The return stroke of the driving link is ended by the contact between the extension of the driving link and the stop on the base plate. However, there""s no device provided to limit the motion of the driving link in the forward stroke, thus increase the damage potential if the lever is over turned.
Based on the findings of the aforementioned drawbacks, it is therefore desirable to introduce a more simplified and precise structure to reduce the cost in manufacturing and enhance the quality of the coin release device.
An object of the present invention is to provide a payphone coin release device, which has a pivotal intermediate link to transmit the force from the driving link to the driven link, to function more precisely when compared with the conventional structure.
Another object of the present invention is to provide a payphone coin release device that could avoid the oscillation of the pivot pin to enhance its quality.
Yet a further object of the present invention is to provide a payphone coin release device that has a driving link with two extensions, which could limit the strokes of the driving link to avoid the damage of the device if one over turns the user-actuateable lever.
To achieve the aforementioned objects, there is provided a payphone coin release device comprising a base plate fixed inside the payphone casing and, having a pivotal pin extending therefrom to rotatably support thereon a driven link having two opposite arms of which one is rotatably pivoted at one end of an intermediate link and the other one rotatably supports thereon a coin release roller to cooperate with a conventional coin receiving device. The base plate also has a hole through which a shaft rotatably extends to drivingly engage a driving link. The driving link has an pin formed thereon to drivingly engage an intermediate link. The intermediate link is pivoted at two opposite ends to both the driven link and the driving link. The shaft of the driving link extends outside the payphone casing and is connected to an user-actuateable lever so that by actuating the lever, the driving link is rotated to drive, through the connection of the intermediate link, the driven link to rotate about the pivot. The driving link has higher and lower extensions to work with a stop provided on the base plate to limit the rotation of the driving link. A biasing spring is provided between the driving link and the base plate to bias the driving link toward an un-actuated position defined by contact engagement between the lower extension of the driving link and the stop on the base plate.
These and other objects and advantages of the present invention will become more apparent from a consideration of the following detailed description of a preferred embodiment thereof, when read in conjunction with the accompanying drawings, wherein: